Preliminary Inspection

1. Refer to INTERMITTENTS  before starting.
2. Verify on-vehicle diagnostics are working by performing DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 4.6L DEVILLE & SEVILLE article.
3. Observe the owners driving habits, if possible.
4. Ensure that the driver understands the transmission Torque Converter Clutch (TCC), and the A/C compressor operation as necessary for appropriate symptom, as explained in the owners manual. Inform the customer how TCC and the A/C clutch operates.
5. Search for Technical Service Bulletins (TSBs).
6. Ensure PCM grounds are clean, tight, and properly located.
7. Check vacuum hoses for splits, kinks, leaks, restrictions and proper connections. Ensure vacuum hoses are correctly routed as shown on vehicle emission control information label.
8. Check for air leaks at all intake manifold sealing surfaces.
9. Check ignition wires for cracking, hardness, proper routing and carbon tracking.
10. Check wiring for proper connections and routing, pinches, burns, cuts or other damage.
11. Ensure PCM and MIL are functioning properly.
12. Ensure there are no DTCs stored, or only intermittent DTCs are present.
13. Ensure that the scan tool data is within normal operating range.
14. Ensure fuel control system is operating properly. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.6L DEVILLE & SEVILLE article.
15. Perform fuel system pressure test. See FUEL SYSTEM DIAGNOSIS under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.6L DEVILLE & SEVILLE article.
16. Perform a careful visual inspection of all systems.

After all checks have been performed, verify customer complaint and locate correct symptom. Check items indicated under that symptom. Not all items listed under each symptom apply to all models and systems. These procedures will normally recommend testing of a specific system or component, such as EGR, ignition, TCC, etc. See SYSTEM & COMPONENT TESTING - 4.6L DEVILLE & SEVILLE article for test procedures.